[registry-facade] Support Docker Image Manifest v2 requests

i.e. support `application/vnd.docker.distribution.manifest.v2+json` as
value for the `Accept` header.

Fixes #2714

Author: Christian Weichel

components/registry-facade/pkg/registry/manifest.go

@@ -109,7 +109,10 @@ func (mh *manifestHandler) getManifest(w http.ResponseWriter, r *http.Request) {
 					continue
 				}
 
-				if mediaType == ociv1.MediaTypeImageManifest || mediaType == "*" {
+				if mediaType == ociv1.MediaTypeImageManifest ||
+					mediaType == images.MediaTypeDockerSchema2Manifest ||
+					mediaType == "*" {
+
 					acceptType = ociv1.MediaTypeImageManifest
 					break
 				}